Study Set Content:
Interconversion of chair conformations, resulting in the exchange of axial and equatorial
positions
Ring-flip
Cyclohexane ring at room temparature
rapidly flips between chair conformations
Two conformations of monosubstituted cyclohexane aren't equally stable
Two conformations of monosubstituted cyclohexane aren't equally stable
Equatorial conformer of methyl cyclohexane is more stable than the axial by
- 7.6 kJ/mol
Substituent is more stable in an
- equatorial position than in an axial position
- Causes steric strain
1,3-Diaxial Interactions
- Causes difference between axial and equatorial conformers
Steric stain
Hydrogen atoms of the axial methyl group on C1 are too close to the axial hydrogens three carbons away on
C3 and C5
- is less stable than anti butane by 3.8 kJ/mol due to steric interference between hydrogen atoms on the two methyl groups
Gauche butane
Four-carbon fragment of axial methylcyclohexane and gauche butane have the same
steric interaction
- Equatorial methylcyclohexane
- has no such interactions
- More stable
A type of alkene hydrocarbon which
contains a closed ring of carbon atoms.
Cycloalkenes: cycloolefin
- comes from ancient Greek and in this case means round.
cyclo
Whenever the ends of a carbon chain are joined together, that molecule is said to be
cyclic
Uses:
of cycloalkenes
- Most important organic substances for biological and industrial purposes because they are used in the production of molecules essential to a broad spectrum of applications.
Cycloalkenes are unsaturated and therefore have fewer
hydrogen atoms and fewer bonds,
Like cycloalkanes, cycloalkenes use what forces to bond
Van der Waals forces
- Macroscopically, most cycloalkenes are liquid at room temperature, though have very low solubility in water. Only the first few cycloalkenes are gases. Cycloalkenes are rarely solid at room temperature. Essentially, cycloalkenes have similar physical properties to alkenes and cycloalkanes aside from the fact that cycloalkenes have at least one double bond.
- Macroscopically, most cycloalkenes are liquid at room temperature, though have very low solubility in water. Only the first few cycloalkenes are gases. Cycloalkenes are rarely solid at room temperature. Essentially, cycloalkenes have similar physical properties to alkenes and cycloalkanes aside from the fact that cycloalkenes have at least one double bond.
- Alkenes contain double bonds, and cycloalkenes benefit from enhanced stability if the double bonds are conjugated.
- Alkenes contain double bonds, and cycloalkenes benefit from enhanced stability if the double bonds are conjugated.
- Cyclohexene is one such case, where if it contains a total of three double bonds it is
no longer called cyclohexene. A six-carbon ring with three alternating (and therefore conjugated) double bonds is called
benzene
